1. Field of the Invention
The present invention relates to techniques of a failover method, a program, a failover apparatus and a failover system.
2. Description of the Related Art
In order to improve the availability of a computer system including a large number of servers, there is a method (failover method) in which a plurality of active servers and one or a small number of spare servers are provided, and once a failure occurs in one of the active servers in use, processing of the active server is taken over to another server (spare server) in the computer system. US2006/0143498A1 has disclosed a technique in which when a failure occurs in any one of active servers, a startup disk connected to the active server is reconnected to a standby server and operated from the standby server so that processing of the active server can be taken over to the standby server. US2007/0136447A1 has disclosed another technique in which one or a small number of spare servers are provided for a large number of active servers so that a highly reliable computer system improved in availability can be constructed inexpensively.
In the techniques disclosed in US2006/0143498A1 and US2007/0136447A1, a spare server to take over operation is retrieved from a server management table where server-specific information concerned with a CPU (Central Processing Unit), a memory, etc. is recorded. In the techniques disclosed in US2006/0143498A1 and US2007/0136447A1, a failure detecting function and a spare server retrieving function are provided but a target of retrieval is the server management table where only the server-specific information is recorded. Accordingly, there is no consideration of configuration information and operating information of devices shared among a plurality of servers such as a power control device for starting up a spare server. For this reason, there is a possibility that a spare server may fail to start up due to a failure or the like in one of shared devices such as NWSWs (Network Switches) or FCSWs (Fibre Channel Switches) connected to respective servers to thereby make it impossible to resume operation. The failover method provided for a computer system requiring high reliability has a problem that there is no suggestion about a function to improve the reliability.
The computer system generally requires as high reliability as that of an expensive computer system having a cluster configuration. The computer system requires sufficiently high reliability to take over operation of an active server and resume the operation surely when a failure occurs.